INTRO: The U-S Marine Corps is investigating allegations that maintenance records for its controversial tilt-rotor Osprey aircraft have been falsified. V-O-A Correspondent Alex Belida reports from the Defense Department.

TEXT: A Pentagon statement says the investigation stems from an anonymous letter and audio tape sent to authorities and made available to the Marine Corps last week.

The statement says the information alleges the commanding officer of the marine's tilt-rotor training squadron in North Carolina asked marines to falsify maintenance records on the squadron's Osprey aircraft.

The commander has been relieved of his duties, pending the investigation.

No further details are provided. But the statement says there appears to be no connection between the allegations and the causes of two fatal Osprey crashes last year.

The most recent, in North Carolina last month, claimed the lives of four marines, including the service's most experienced Osprey pilot. That crash remains under investigation.

The Marine Corps' small fleet of test model Osprey aircraft remains grounded pending the outcome of that probe. The Pentagon has also put off a decision on whether to go ahead with full-scale production of the aircraft.

The Marine Corps hopes to acquire more than 350 of these tilt-rotor aircraft, which take off and land like helicopters but otherwise fly like conventional winged airplanes.

The Osprey is intended to replace the Marine Corps' aging fleet of helicopters and other aircraft.